Gas adsorption beds are used in many industries to remove gaseous contaminant from the air to protect people, the environment and, in many cases, a manufacturing process. Gas adsorption beds are also used in sick buildings and other enclosed spaces.
One specific application of gas adsorption beds is in the semiconductor industry where product is manufactured in an ultra-clean air environment, commonly known as a clean room. Invariably, a manufacturing process will require the use of a solvent or an aerosol to be used in the clean-room environment. This presents a problem because gaseous contaminant coming from the process will contaminate the air and other processes in the room. To eliminate the problem, the contaminated air is drawn through a granular adsorption bed assembly having a frame and a bed of adsorption medium, such as activated carbon, disposed within the frame. The adsorption medium adsorbs the gaseous contaminant from the airstream and allows the clean air to be returned to the room.
The removal efficiency and holding capacity of a gaseous adsorption bed is dependent upon a number of factors, such as the air velocity through the adsorption bed, the depth of the adsorption bed, the type and amount of adsorption medium used, and the activity level of the adsorption medium. One other significant factor that effects adsorption efficiency is the amount of contaminated air that can leak through voids between the adsorption bed and the frame, and leak through frame joints. It is also desirable to promote even deterioration or wear of the activated gas adsorption bed by equally distributing the flow of air incident the adsorption bed across its cross-sectional area. Further, if more than one gas adsorption bed is used in an installation, it is desirable to deliver equal amounts of contaminated air to each adsorption bed so that they will wear or deteriorate at approximately the same rate.